Chemotheraphy-induced peripheral neuropathy (CIPN) limits life saving anti-cancer treatment, can be permanent and negatively impacts quality of life. It is thus important to dissect the critical signaling pathways involved in development an maintenance of CIPN and identify therapeutic strategies to prevent or treat CIPN. The NMDA receptor (NMDAR) signaling complex plays a key role in central sensitization of chronic pain. While NMDAR antagonists are efficacious in decreasing pain sensitization, they have limited therapeutic uses because they disrupt normal physiological processes (e.g. motor function, memory and cognition). The NMDAR signaling complex consists of many protein partners including the scaffold postsynaptic density 95 kDA (PSD95) protein, the neuronal enzyme nitric oxide synthase (nNOS) and its adaptor protein NOS1AP. Disruption of specific steps downstream of NMDAR activation offers the opportunity to decrease pain sensitization while avoiding some of the broader side effects associated with upstream receptor blockade. Our preliminary studies suggest that the interface between nNOS and NOS1AP represents a previously unrecognized candidate target for the development of new analgesics for CIPN. Aim 1 will determine whether disruption of nNOS interactions with its upstream or downstream protein partners bias NMDAR signaling in a functionally selective manner using biochemical and cell based assays. Aim 2 will evaluate the therapeutic potential of disrupting the nNOS-NOS1AP protein-protein interface for suppressing neuropathic pain induced by the chemotherapeutic agent paclitaxel and correlate antinociceptive efficacy of intrathecally administered agents with disruption of the nNOS-NOS1AP complex in lumbar spinal cord of paclitaxel-treated rats. Aim 3 will identify signaling pathways downstream of NOS1AP that underly the ability of nNOS-NOS1AP inhibitors to attenuate paclitaxel-induced neuropathic pain. In this project, the mechanism by which peptide and small molecule protein-protein interaction inhibitors to selectively block NMDAR-induced hypersensitivity in a paclitaxel-induced neuropathic pain model will be elucidated. If confirmed, a new generation of modulators of pathological pain could be developed by targeting this interaction.